Adjusting the CAC
Configuring the CAC
ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000 1/19/05A-5
Beta Draft Confidential
Tuning the CAC
To tune the CAC, specify the CLR objectives you want to meet across your network.
You can specify a CLR objective in the range of 10
-1
to 10
-12
. For example, an entry of
10
-5
specifies that circuits will not be created on any physical port on which the:
• CDR is currently 1 in 100,000 (because 10
-5
is equal to 1/100,000),
or
• creation of the circuit would potentially cause the cell drop ratio to exceed
1 in 100,000.
To tune the CAC:
1. In the Set All CAC Parameters dialog box (Figure A-1 on page A-4), select
Lucent in the CAC Type field.
2. In the Cell/Frame Loss Ratio field, VBR Real Time and VBR Non-Real Time,
specify the CLR objective you want to meet for each of these traffic types. This
value is a negative power of ten (1.0e–). For example, if you enter 5, your CLR
objective is a maximum of one dropped cell for every 100,000 cells. If the CAC
determines that the creation of a circuit on a physical port will cause more than
one in 100,000 cells to be dropped, then the circuit will not be created on that
physical port.
By default, VBR Real Time is set to 9 (1 in 1,000,000,000) and VBR Non-Real
Time is set to 6 (1 in 1,000,000).
3. In the Cell/Frame Delay Variations field, CBR and VBR Real Time, specify the
CBR and VBR-RT in microseconds (
µsec). These values represent the CDV
objective for the CBR and VBR-RT QoS class. Although the CDV value
represents an upper bound on the delay variation for most physical interfaces, the
CAC algorithm allows the actual CDV values on slow interfaces (such as T1
cards) to exceed this configured value.
Note – Lucent recommends that you adjust the CAC when you first configure a
switch. Adjusting the CAC after several circuits have been created will not
automatically change the bandwidth allocation for these circuits and may not
guarantee the defined QoS.
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